These forces are opposite to each other Lift Gravity Thrust
Drag
Slide 6
Forces necessary for flight Gravity Drag Lift Thrust Forces are
pushes or pulls.
Slide 7
Definitions 1. Gravity A force that pulls objects towards the
earth. 2. Lift acts in the opposite direction to the force of
gravity (pushes objects up). 3. Thrust Pushes the plane forward. 1.
Jet engine 2. Propellers 4. Drag - acts in the opposite direction
to thrust (pulls plane back). For a plane to rise, the force (F) of
lift must exceed (be greater than) the force of gravity. There
needs to be an unbalanced force. Vector a vector shows direction
and the magnitude (strength) of a force.
Slide 8
Diagram Vectors LIFT GRAVITY
Slide 9
Example 1 Forces are equal. Plane not rising or falling.
Slide 10
Wings and Bernoullis Principle When a fluid (water, air) such
as air moves quickly it creates low pressure. Air foil
Slide 11
air A AA A A A ir Fast moving air creates low pressure. Slower
moving air creates high pressure.
Slide 12
air Air splits up Leading edge
Slide 13
Bernoullis Principle Slower air (high pressure) Faster air (low
pressure) High pressure always tries to move to low pressure. The
High pressure at the bottom of the wing tries to get to the low
pressure at the top. The high pressure cannot pass through the wing
so it pushes upward. The wing is connected to the body of the
plane. As the wing rises (lifts) the plane rises with it.
Slide 14
Drag Drag is a force that acts in the opposite direction of
thrust. Large flat surfaces bring up in a lot of air particles.
They do not pass easily through the air. For these surfaces air
resistance or drag is great. To overcome this, planes have a sleek
design so that they can easily pass through the air. Designing a
plane in such a way is known as streamlining. In otherwords it is
more aerodynamic!
Slide 15
Non-aerodynamic and Aerodynamic An Old Truck is boxy and has
more drag. Todays Trucks are more aerodynamic and streamlined. They
have less drag.
Slide 16
Example of aerodynamic car Todays cars are more rounded and
have less drag.
Slide 17
Newton Newton: everything pushed on, pushes back. * The high
pressure beneath the wing tries to get to the low pressure at the
top. In doing so it pushes on the wing and lifts the plane.
Slide 18
Thrust Thrust: Type 1 Propellers More common on older type
models of planes. Big blades on wings and nose of plane push air
back over the plane moving the plane forward (think of you swimming
- you push water back behind you, you move forward). Propeller
driven planes are: 1. Cheaper to build 2. More reliable 3. But not
so fast as jet engine planes.
Slide 19
Airplane Controls Elevators: These are hinged sections at the
back of a plane. They are usually found on the tail wing of a
plane. Elevators up rear of the plane is pushed down. The nose goes
up. Elevators down the back of the plane is pushed up and the nose
goes down. Going up or down is called the pitch.
Slide 20
Pitch, Roll and Yaw
Slide 21
Rudder Rudder: Yaw is the motion of a plane as the nose turns
left or right. It is controlled by the rudder. Left rudder nose
turns left Right rudder nose turns right (See diagram on next
slide).
Slide 22
Left and Right Rudder
Slide 23
Ailerons Ailerons are used to control the roll of a plane
(banking).
Slide 24
Right and Left Ailerons Right aileron up, left aileron down.
What happens? plane rolls or banks to the right. Left aileron up,
right aileron down. What happens? Plane rolls or banks to the
left.
Slide 25
Parts of an Airplane (see handout) Cockpit Fuselage (body) Jet
engine Aileron Horizontal stabilizer Elevator Rudder Vertical
stabilizer Wing Trailing edge Leading edge Know the words in red
for the test.
Slide 26
Parts of a Plane
Slide 27
Slide 28
Airplane # 1 is banking right. I know because the right aileron
is up and the left aileron is down.
Slide 29
Airplane # 2 is climbing. I know this because the elevators are
up.
Slide 30
Airplane # 3 is yawing right. I know this because the rudder is
turned right.
Slide 31
Review of Notes
Slide 32
Project Design an Airplane
Slide 33
Birds and Flight Bird wing (See diagram) Leading edge Trailing
edge The picture above shows the side view of a birds wing which is
similar to the wing of a glider, airplane, or helicopter blade. 1.
When air hits front of wing (leading edge) it splits up. 2. The air
flowing over the curved top of the wing has farther to go than the
air going under the flat of the wing. 3. For the two streams of air
to reach the back of the wing (trailing edge) at the same time, the
top stream of air must travel faster (it has farther to go). 4.
This fast moving air creates a low pressure area on top of the wing
and a high pressure area on the bottom of the wing (Bernoullis
Law). 5. Since objects (air) tend to go from high pressure to low
pressure, lift is created which is how both birds and planes stay
up in the air. Note: For the wing to have lift, it must be moving
forward through the air.
Slide 34
Slide 35
Birds Wing
Slide 36
How Birds Fly 1. Like planes, birds are streamlined, and 2.
built of light materials so that they can fly. Feathers point
backwards on a bird. Bills are lighter and more streamlined than
the heavy jaws of a person or bear. Most birds bones are hollow and
filled with air from the birds lungs, even the wishbone is
hollow.
Slide 37
How Birds Fly continued Study for test. Birds move through the
air by pulling themselves forward like a person rowing a boat. They
push air down and back with the broad side of their wing, then
slightly turn and fold the wing to move it forward. Birds with
broad wings can soar and glide for long periods without flapping.
Birds have to flap fast to stay in up. Bird wings and airplane
wings have a similar shape. This shape provides lift.
Slide 38
Slide 39
Birds Wing
Slide 40
Wind Tunnels Study for test Wind tunnels are a device that
allows model planes to be monitored (observed) while the wind is
blown over them. The models are tested to see how aerodynamic or
streamlined their shapes are. Wind tunnels are valuable because it
is much cheaper to test model sized planes than to build very
expensive full-sized planes. If the design is bad, then we would
have wasted a lot of money.
Slide 41
Rockets versus Airplanes Rockets Airplane Need to overcome
gravity and air resistance to get into space. As you get further
from earth air resistance and gravity decreases. Shape (has fins)
Speed faster Larger engines that require more fuel Space
exploration Missions are in months or years After launch gravity
reduces with altitude. Rocket engines are more powerful and burn
more fuel. They have stages that fall off as they go further into
space. Needs lift to overcome gravity provided by thrust and wing
shape. Thrust must exceed air resistance. Shape (has wings)
Designed for passenger travel (hours) Thousands of flights per day
Fly for hours Always has strong gravitational forces on it.
